Unloader for fluid compressors



May 12, 1953 H. BROWNE 2,533,264

UNLOADER FOR FLUID COMPRESSORS Original Filed. March 2, 194s s Sheets-Sheet 1 INVENTOR.

Arrvs.

LINDSAY H. Beam/E BY 4 Patented May 12, 1953 UNLOADER FOR FLUID OOMPRESSORS Lindsay H. Browne, Weston, Gonna assignor to American Brake Shoe Company, Wilmington, Del., a corporation of Delaware Original application Marc'h 2,,1948, Serial No. 12,610. Divided and this application March 16, 1951, Serial No. 215,977

This application is a division of my co-pending application, Serial No. 12,610, filed March 2, 1948.

This invention relates to unloaders for fluid compressors, such :as-air compressors, and the primary object of my invention is to afford an unloader which will not only be effective during the start of operation of the compressor with which it is associated, but also will become effective in the event of improper operation of the compressor, such as a. reduction in the speed thereof or failure of the lubricating system thereof.

Other objects of this invention are to associate a novel unloader with a compressor embodying a forced feed lubricating system and to connect the unloader to the lubricating system in such a way that pressure failure in the lubricating system will cause the unloader'to effect its unloading function; to associate an unloader with rotative parts of a compressor in such a way that when the compressor is operating at its proper, normal speed, the attendant forces will be effective to prevent the unloader from effecting its unloading; and to associate a novel unloader with a fan that is set in operation upon operation of the compressor whereby the operation of the fan will be effective to control operation of the novel unloader.

A yet further object of this invention is to provide'a novel unloader of simple and economical construction and which will be eilicient and positive in operation. I

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and What I now consider to be the best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled'in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. l is a vertical sectional view of a compressor of the kind with which my novel unloader may be associated and showing mynovel unloader in association with such compressor;

Fig. 2 is a vertical sectional view through one I form of my novel unloader and showing the same in condition to effect unloading of the associated compressor, and taken substantially on the line 2-2 on Fig. 4;

7 Claims. (Cl. 2307 Fig. 3 is a view similar to Fig. 2, but showing the unloader in condition to prevent unloading of thecompressor;

Fig. 4 is a plan view of the unloader as shown in Fig. 2;

Fig. 5 is a planview of a modified form of my novel unloader;

Fig. 6 is a view similar to Fig. 2, but showing the modified form of my unloader that is illustrated in Fig.5;

Fig. 7 is another vertical sectional view of the unloader shown in Figs. 5 and 6, and taken substantiallyon the line 1-1 on Fig. 5; and

Fig. 8 is an enlarged detail view of a portion of the unloader shown in Fig. 2. I

. --The compressor with which my novel unloader is associated embodies a compressing unit that is driven by the motor generally indicated by 32 and which includes a stator 36 that is secured to the housing 39, the motor also including a rotor 31 which is keyed or-otherwise suitably secured to the main drive shaft of my novel compressor, snap rings 41 and 48 being effective to prevent longitudinal movement of the rotor along the shaft 45.

--The casing 39 is supported from the casing 43 which houses the compressing means embodied in my compressor. This housing includes an upper end portion 54 in which a ball-bearing 52 is 'journaled and the shaft 45 is connected to the inner race of this ball-bearing. At the lower end of the casing 43 there is a sleeve I3 which supports a ball-bearing I4, and a reduced portion at the lower end of the shaft 45 is mounted in theinner race of this ball-bearing. Thus,

bearings 52 and I4. Two substantially oppositely disposed crank cams 84 and 86 are provided on the shaft 45 intermediate the ball-bearings 52 and I4. Counterweights and 81 are also provided on this portion of the shaft 45.

A yoke IllI is mounted on the cam block 88 and the end portions I03 and I05 of this yoke afford substantially rigid connecting rods H0 and I II which, respectively, carry the pistons H3 and H4, these pistons being reciprocal in diametri- I cally opposed cylinders H6 and Ill, respectively, the cylinders being afiorded in the casing or housing 43. I

Another yoke I40, similar to the yoke IIJI is mounted on the cam block 89. The end portions I42 and I43 of the yoke I40 include substantially rigid connecting rods I58 and I59 which, respec- "tively reciprocal in diametrically opposed cylmove-the shoulder 424 down out of engagement with the valve head MB. This movement of the fan 31'!) and the shoulder 424 of the ring 426 frees the valve 4 I 8 for downward movement, and, therefore, the spring 456 is effective to move the valve M8 downwardly and thereby move the disc 42l into engagement with the valve nipple 438 to thereby close the passageway 436 and load the compressing unit.

At any time during the operation of my novel 1 compressing unit if the speed of rotation of the drive shaft 45, and, therefore, if the fan 310 falls below a predetermined speed, or, if the pressure of'the oil discharged by the oil pump 80 falls below a predetermined pressure, the spring 456 is rendered ineffective to maintain the valve disc 42| in closed position on the valve nipple 438 and the compressing unit is unloaded. Thus it will be seen that my novel unloader 210 comprises an effective means for maintaining my novel compressing unit unloaded during the starting thereof until the speed of operation and the oil pressure have raised to their normal amounts, and also comprises a safety unit for unloading the compressor during operation of my compressing unit if either the speed of operation or the oil pressure falls below a predeter- -mined amount.

.When my novel compressing unit is mounted in the previously discussed horizontal position for operation, the operation of the unloader 210 is substantially the same as when the compressing unit is in the vertical position just discussed,

the principle difference being that the springs to! and 602, unassisted by the force of gravity on the fan 379 are relied on to hold the fan 310 in normal, lowered, position.

A modified form of unloader 210a, adapted to be used on my novel compressor, is shown in Figs. 5, 6 and '7 where parts which are similar to parts described hereinabove are indicated by the same reference numerals with the suflix a. added thereto.

,As is best seen in Figs. 6 and '7, the unloader 210a comprises an upper body member 3980. having a recess 404a formed therein, and a lower body member 40011 having a recess 405a formed therein and a shaft 409a extending therefrom. The two body members are held together by bolts 402a and a diaphragm 401a is positioned between the two body members.

The lower body member 400a has an inlet passageway 436a formed therein having an enlarged chamber 500 opening into the recess 405a.

The chamber 500 has two valve seats 50! and 504 formed therein and a valve 505, having two heads 50'! and 508,'adapted to seat on the valve seats 502 and 594, respectively, is mounted on the upper end portion of a valve rod 396a. A spring 456a, mounted in the shaft 409a and engaged .nected to the coupling member 452 on the exhaust tube 454, is also formed in the lower body member 400a andis connected to the recess 405a by a passageway SN, and to an extension cham- .ber N2 of the enlarged. chamber 500 by a pasas ay A valve ring 426a having a shoulder 430a, a flange 424a, and a base 428a is mounted within the recess 405a on a compression spring 4340.. A

thrust plate 432a rests on the shoulder 430a below the diaphragm 401a, and a valve plate .4 i 8a mounted on the upper end portion of the valve 505 is adapted to be engaged by the flange 424a.

Another passageway 442a, adapted to be con- .nected to the coupling member M8 on the end of the oil tube 294 which extends from the oil pump .80, is formed in the lower body member 400a and is connected to the recess 404a by a passageway 446a.

Two bearings 4| la and 412a are mounted on the shaft 409a whereby the unloader 210 may be journaled in the upper end portion of the camshaft 45 of my novel compressor.

The modified form 2151a of my unloader operates in substantially the same manner as the unloader 210, with the exception that the valve .500 is of the so-called balanced valve type,

whereby the pressure of the air in the passageway 436a exerts substantially equal opposite forces on the valve heads 51!! and 508 to thereby eliminate the tendency of the air pressure to unseat the valve 500. Also it will be seen that unlike the unloader 210, when the valve 500 is in open or unloading position, air can pass from the pressor.

Hence, my novel unloader enables the hereinabove set forth and kindred objects of this invention to be realized and, while I have illustrated and described the preferred embodiments of my invention, it is to be understood that these are capable of variation and modification, and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. An unloader of the type adapted to be used on a compressor having an oil pump, comprising a valve operable in one position to effect loading of such a compressor and out of said position to eifect unloading of said compressor, means adapted to move said valve into said one position, said means including a spring connected to said valve and fluid pressure actuated means respon- .sive to oil under pressure from the oil pump of such a compressor during the operation of the latter, and other means including a second spring and a. lever disposed in position to operatively engage said valve for rendering said first named -means inoperative to move said valve into said one position when either the speed of operation of the compressor is below a predetermined speed or the pressure of the oil discharged by the pump of the compressor is below a predetermined pressure, said other means being inefiective to render said first named means inoperative to move said valve to said one position when the speed of the compressor is above a predetermined speed and the pressure of the oil discharged by the oil pump of the compressor is above a predetermined pressure.

2. In an unloader of the type adapted to be used with a compressor having a drive shaft 7 rotatably mounted, therein, a fan slidably mounted on said drive shaft for rotation therewith, and an oil pump connected to said drive shaft and operable to pump oil under pressure upon rotation of said drive shaft, the combination of a housing having a chamber formed therein, a valve reciprocably mounted in said chamber, said valve being operable in one position to effect loading of such a compressor and out of said position to effect unloading of such a compressor, means adapted to move said valve into said one position, said means including. a spring connected to said valve and urging said valve toward said one position, a thrust plate movably mounted within said chamber, and a flexible diaphragm engaged with said thrust plate and responsive to oil under pressure from the oil pump upon operation of the latter to move said thrust plate toward said valve, and other meansf'or rendering said first named means inoperative to move said valve into said one position when either the speed of rotation of the fan. of the compressor is below a predetermined speed or the pressure of the oil discharged by the oil pump of the compressor is below a predetermined" pressure, said other means including an annular shaped member engageable with said thrust plate and having a shoulder engageable. with said valve, a second spring. engaged with said annular shaped memher and urging said thrust plate and said valve away from said one position, and a lever engageable with said valve and adapted to. be controlled by the fan of the compressor, said other means being ineiiective to render said first named means inoperative to move said valve. to said one position when the speed of rotation of the fan of the compressor is above said predetermined speed and the pressure or oil discharged by the oil pump of the compressor is above said predetermined pressure.

3. An unloader of the type. adapted to be used on a compressor having an oil pump, comprising a valve operable in one position to. sheet loading of such a compressor" and out oi? said position to effect unloading of said compressor, means operable to move said valve. into said one position, said means including a spring connected to said valve and a diaphragm responsive to oil under pressure from the oil pump of such a compressor during the operation of the latter, and other means for rendering said first named means inoperative to move said valve into said one position when either the speed of operation of the compressor is below a predetermined speed or the pressure of the oil discharged by the pump of the compressor is below a predetermined pressure, said other means including a second spring, operatively connected to said valve in opposition to said first named spring, a fan rotatable by said compressor, said fan being slidable longitudinally to the axis of rotation in response to changes in rotative speeds thereof, and a lever engageable with said fan and said valve, said other means being ineffective to render said first named means inoperative to move said valve to said one position when the speed of the compressor is above a predetermined speed and the pressure of the oil discharged by the oil pump of the compressor is above a predetermined pressure.

4. In a compressor comprising a base, a housing mounted on said base and embodying oppositely disposed cylinders, pistons reciprocably mounted in said cylinders, valve means for controlling the flow of working fluid into and. out of said cylinders, discharge means connected to. said cylinders, a drive shaft rotatably mounted in said housing, means connected to said drive shaft and said pistons for reciprocating. said pistons. in said cylinders upon rotation of said drive shaft, 2, motor mounted on said drive shaft for rotating the latter, an oil pump connected to said drive shaft for operation thereby, and a fan slidably mounted on said drive shaft for rotation therewith, an unloader connected to said discharge means and. operative to open and close said discharge means to the atmosphere, conduit means operatively connecting said unloader to said oil pump, and lever means operatively connecting said unloader to said fan, said unloader being operative' to maintain said discharge means open to the atmosphere when the speed of rotation of said. fan is below a predetermined speed or the pressure of the oil pumped by said oil pump is below a predetermined pressure and being adapted to close said discharge means to the atmosphere when the pressure of the oil pumped by said oil pump is above a predetermined pressure and the speed of rotation of said fan is above a predetermined speed.

5. In a compressor comprising a housing embodying. diametically opposed cylinders, pistons reciprocably mounted in said cylinders for compressing working fluid therein, a. drive shaft extending between said opposed cylinders substantially transversely thereto, means intermediate said drive shaft for reciprocating said pistons in said cylinders upon rotation of said drive shaft, valve means controlling the intake and exhaust of working fluid relative to said cylinders, discharge means connected to said cylinders for passing working fluid therefrom, and an oil pump connected to said drive shaft and operable thereby upon rotation of the latter, an unloader including a body having a chamber therein and a flexible diaphragm extending across and dividing said chamber, means including a passageway formed in said body for establishing communication between said discharge means and said chamber on one side of said diaphragm, a valve seat carried by said body at one end of said passageway, means including a passageway formed in said body for establishing communication between the atmosphere and said chamber on said one side of said diaphragm, means including a passageway formed. in said body for establishing communication between said oil pump and said chamber on the other side of said diaphragm through which said oil pump is efiective to discharge oil under pressure into said chamber during rotation of said drive shaft, a valve reciprocably mounted in said body and operable to be moved into and out of engagement with said valve seat, said valve being operable when in engagement with said valve seat to close said first named passageway and thereby close com munication between said discharge means and said chamber, a spring yielda'bly urging said valve away from said seat, a second spring urging said valve toward said valve seat, said second spring being weaker than said first mentioned spring, a lever pivotal'ly mounted on said drive shaft and having one end in engagement with said valve, a fan slidably mounted on said drive shaft for rotation. therewith and engageable with the other end of said lever, said fan normally engaging said other end cf said lever and urging said valve away from said valve seat, said fan being so disposed on said shaft that during rotation of said drive shaft said fan is urged to slide away from said lever, said fan and said first mentioned spring being effective to hold said valve off of said valve seat when the pressure of the oil discharged into said chamber by said oil pump is below a predetermined pressure, or when said drive shaft is rotating at less than a predetermined speed, said fan and said spring being rendered ineffective to hold saidvalve out of engagement with said valve seat when the pressure of the oil discharged into said chamber is above said predetermined pressure and when the drive shaft is rotating at more than said predetermined speed.

6. The combination defined in claim and in which said first mentioned means including a passageway includes a second valve seat extending around a portion of said passageway, and in which said valve includes two head portions disposed in position for movement into and out of sealing engagement with respective ones of said valve seats on the sides thereof adjacent said chamber during said operable movement of said valve, and in which said second mentioned means including a passageway includes another passageway connected to said last mentioned passageway and connected to said first mentioned passageway on the opposite side of said second valve seat from said chamber.

7. An unloader of the type adapted to be mounted on an air compressor of the type including a discharge conduit for air compressed by the compressor, a rotatable drive shaft and a fan mounted on one end portion of said drive shaft for rotation therewith, said fan being slidably mounted on said drive shaft for movement longitudinally relative thereto, said unloader comprising an elongated housing having one end portion adapted to be mounted in said one end portion of said drive shaft, a chamber defined in the other end portion of said housing, a diaphragm extending across said chamber and separating one end portion of said chamber from the other end portion thereof, a conduit extending through said other end portion of said housing into said other end portion of said chamber and adapted to connect said other end portion of said chamber to said discharge conduit, of such a compressor, a second conduit extending through said other end portion of said housing into communication with said other end portion of said chamber and connecting said other end portion of said chamber to the atmosphere, a third con-- duit extending through said other end portion of said housing into communication with said one end portion of said chamber and adapted to connect said one end portion of said chamber to the oil pump of such a compressor, an elongated valve extending through said one end portion of said housing and having a valve head mounted in said other end portion of said chamber, said valve being movable longitudinally of said housing into and out of engagement with said first mentioned conduit to thereby open and close said conduit and control the loading and unloading of such a compressor, a compression spring operatively connected to said valve and urging said valve away from said first mentioned conduit, means engaged with said diaphragm for urging said valve toward said conduit, a lever adapted to be pivotally mounted in said drive shaft with one end of said lever disposed in engagement with one end portion of said valve and the other end portion of said lever projecting outwardly from said diaphragm first into position for engagement with such a fan when said fan moves through a predetermined path of movement on said drive shaft longitudinally of the latter, for restraining the movement of said valve toward said valve seat, and a spring mounted in said housing and connected to said valve for urging said valve into engagement with said first mentioned conduit, said last mentioned spring being ineffective to move said valve into engagement with said first mentioned conduit against the urging of said first mentioned spring and the restraint of said fan 1 on said lever when the pressure of oil fed into said one end portion of said chamber is below a predetermined pressure or the speed of rotation of said drive'shaft is below a predetermined speed.

LINDSAY H. BROWNE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,047,489 Pfeifer July 14, 1936 2,137,219 Aikman Nov. 22, 1938 2,211,875 Aikman Aug. 20, 1940 2,445,527 Hirsch July 20, 1948 

